How can I adjust speed on Ariston Q Deck?

I have a Ariston Q Deck and it has lately been running at the wrong speed when I play any 33-1/3 records on it, it's just a hair slower than it should be. Does anyone out there know how I can adjust the speed or what the problem might be? Thanks,
I answered one of these questions over at Vinyl Engine and the cure was to use a regulated not unregulated power supply to power the table.So try that a DC 12V 350Ma at least.
Yes there are a number of avenues to try and the guy over at The Vinyl Engine fixed his speed problem with a regulated supply.The belt suggestion is good and I would check to see there is lubrication in the spindle-well also.A thicker type of oil is recommended here.I recall they stated in the manual you only had to oil it once for life!Anyway let us know how you go.